wwdump: fail ast mode on parser errors

selfhost/cmd/wwdump/main.ww

@@ -114,6 +114,7 @@ export fn main(argc: i32, argv: **u8) i32 = {
 		parserinit(&ps, &l);
 		let f: *node = parsefile(&ps);
 		astprint(1i32, f);
+		if (ps.errs > 0) { return 1; };
 	} else { if (mode == 114) {	// '-r' — name resolve report
 		let ps: parser;
 		parserinit(&ps, &l);

test/tool/wwdump_test.ww

@@ -135,6 +135,10 @@ fn dumprow(td: str, name: str, mode: str, src: str,
 		"package main;\nexport fn main() i32 = { return 0; };\n");
 
 	let co: testenv.commandout;
+	dumprow(td, "bad_a", "-a", badp, &co);
+	if (co.code == 0) {
+		fail("bad_a", "AST dump returned rc=0 on parse-errored input");
+	};
 	dumprow(td, "bad_c", "-c", badp, &co);
 	if (co.code == 0 || co.stdout.len != 0) {
 		fail("bad_c",